The present invention relates to biodegradable surgical implants.
This application relates to U.S. application Ser. No. 09/465,789, filed on Dec. 17, 1999, relating to a device for inserting stents. The disclosure of that patent application is hereby incorporated by reference in its entirety.
In surgery, it is known to employ biodegradable, elongated (typically tubular) surgical implants for supporting, connecting or separating elongated organs, tissues or parts thereof, such as canals, ducts, tubes, intestines, blood vessels, nerves etc. The biodegradable material degrades in vivo and the dissolution products leave the system, e.g., through metabolic ducts, kidneys, lungs, intestines and/or skin by secretion.
Tubular, biodegradable surgical implants involve several drawbacks and limitations, migration being one of them. An injury being treated with a bioabsorbable implant will only heal properly if the implant remains in its intended location within the body, i.e., if the implant does not migrate after implantation. The implants manufactured with previously-known techniques and biodegradable materials do not necessarily prevent migration because they often do not attach themselves tightly enough to the walls of the body cavity, e.g., a blood vessel, being treated.
U.S. Pat. No. 5,792,400 to Talja et al. is related to a method of producing a surgical implant or part thereof made of biodegradable material for supporting, joining and separating tissue and keeping open a tissue cavity. The surgical implant has a helical configuration. However, those biodegradable materials having suitable degradation rates to be used for healing the injury normally have a rather long period of self-expanding after the insertion, which increases the risk that the implant will migrate after insertion.
WO 97/11724 to Txc3x6rmxc3xa4lxc3xa4 et al. also discloses a biodegradable implant. The macroscopic structure of the implant comprises two or several zones, which are created in a manner that they have different degradation times. This technique does not, however, define any preparatory measures for achieving functional modification of the surgical implant, for instance, the self-expansion property of the implant, in order to prevent migration of the implant.
It has been surprisingly discovered in this invention that the migration of biodegradable surgical implants used for supporting, connecting or separating organs, tissues or parts thereof can be substantially eliminated. This invention relates to a biodegradable implant or the like manufactured of polymer-based material and intended to be installed in vivo. The biodegradable implant comprises at least two sections manufactured of different polymer-based materials and joined together to form at least a part of the implant, wherein
the first section has first period of degradation and self-expansion in vivo, and
the second section has second period of degradation and self-expansion in vivo.
By using the implant of the present invention and selecting the periods of degradation and self-expansion appropriately, it is possible to ensure a rapid and firm fixing of the implant after its installation. The second portion of the implant will rapidly expand, thereby affixing the implant securely in its intended location, e.g., a blood vessel or other duct. The first section of the implant, which degrades more slowly than the second section of the implant, will expand more slowly than the second section of the implant. While the first section of the implant is expanding, the second section of the implant, which has already expanded, is helping to ensure that the implant does not migrate. Once the first section of the implant has expanded and is affixed securely in its intended location, it will provide the longer-lasting structural support that is needed. Once the first section of the implant has expanded and has affixed itself to the intended location, the second section of the implant may biodegrade, leaving the first section of the implant in place.